Older adults with HIV are a growing population due to improvements in both HIV treatment efficacy and increasing rates of newly-diagnosed infections in this age group. Chronic pain and substance abuse are prevalent medical conditions in HIV-infected persons. First, painful conditions such as peripheral neuropathy and associated disability are common among those living with long-term HIV infection. Second, advancing age is associated with increasing rates of painful conditions such as osteoarthritis and other musculoskeletal conditions (e.g., back pain). Third, substance abuse is common among persons living with HIV and complicates the treatment of chronic pain in this population. For HIV-infected persons with both chronic pain and substance abuse, an integrated treatment approach is more likely to be of benefit than treating each disorder separately, and a behavioral approach that reinforces self-management could minimize usage of pain medication (a preferable strategy for persons already struggling with substance abuse and polypharmacy). Additionally, chronic pain frequently leads to activity restriction and corresponding functional decline, and interventions that target functional impairment in addition to pain and substance use are needed. Exercise has been shown to decrease pain and improve functional capacity, confidence and mood. In patients who also use substances, the benefits of exercise may result in reduced substance use. The study proposed seeks to combine two evidence-based behavioral therapies, CBT for chronic pain and CBT for substance abuse, and an exercise, flexibility and balance intervention, tai chi, (EX) to be delivered in a group setting. Motivationa reinforcement messaging, a method proven useful in other studies addressing substance abuse and pain control, will be used to enhance the efficacy of the integrated intervention. To conduct the proposed study, we will partner with Core Community Health Center (CCHC), a non-profit, community-based health center that has provided mental health, substance abuse, and (more recently) comprehensive HIV medical care to an ethnically and racially diverse community in Los Angeles, CA since 1987. The goals of the proposed program are to decrease pain perception, pain-related disability and substance use for older, HIV-infected adults with chronic pain and substance abuse. The long-term goal of this research is to develop an effective intervention to improve chronic pain and substance abuse among older adults living with HIV that can be feasibly delivered by community-based health centers serving aging adults with HIV infection.